Mercury switch relay



I Jan. 12, 1937. Q HEDlN MERCURY swncn RELAY Filed Au 17, 1955,

Patented Jan. 12, 1937 UNITED sTATEs MERCURY SWITCH RELAY Uno C. Hedin, Elkhart, Ind., assignor to The Adlake Company, a corporation of Illinois Application August 1'1, 1935, Serial No.36,704

. 11 Claims. (Cl. 200'-112) The efficiency of any electro-magnetic relay is to a large extent dependent upon the characteristics of the iron circuit associated with the switching element and its arrangement with respect to the switching element. It is a primary object of this invention to improve upon the iron circuits heretofore used with mercury switches of the type disclosed in Larson 1,967,247, issued July 24, 1934, and to reduce the power necessary for operating them.

Further objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawing, in which Fig. 1 is a vertical, sectional view showing a preferred form of the invention;

Fig. 2 is an end elevational view of the relay;

Fig. 3 is a perspective view showing the component parts of the iron circuit, the parts being somewhat displaced for clarity of illustration;

and

Fig. 4 is a plan of the relay.

The illustration and specific description of a preferred form of the invention are for the purpose of complying with section 4888 of the revised statutes, and the appended claims should not be construed as limited to the particular form shown and described unless required by the prior art.

The relay comprises a coil l0, an iron circuit generally designated l I, and a switching element l2, the latter taking the form of a mercury switch of the mercury displacement type. The details of the switch are unimportant here, and it will suflice to point out that the switch comprises a switch envelope l3 of boro-silicate glass, electrodes l4 and I5 sealed through the base of the envelope (the latter electrode being surrounded for a portion of its length by a sleeve l6 of insulating material), a mercury fill I1, and a displacer generally designated l8 comprising an inner tube l9 of ceramic material over which a sleeve 20 of magnetic material is telescoped. Guide washers 2| of hardened steel fit against the ends of the armature sleeve 20 and are held in place by springs .22 which frictionally engage the'walls of the inner tube l8.-

It will be understood that when the displacer I8 is in the position shown in Fig. 1, the mercury fill within. the switch envelope closes the circuit between the electrodes l4 and I5, but when the displacer is raised by energization of the coil in, the mercury level falls below the bared end 23 of the central electrode I5 and opens the circuit through the switch.

The lower portion of the switch is encased within a base comprising a bakelite sleeve 24 which is held in place by a suitable sealing compound 25. The base serves the purpose not only of protecting the electrode seals from damage but also prevents short circuiting of the switch by accidental crossing of the exposed ends of the electrodes and their leads.

The iron circuit ll associated with the switch ing element comprises a laminated yoke 21 made of Allegheny transformer electrical sheet iron, the ends 28 and 29 of the yoke extending above and below the relay coil.

Attached to the ends of the yoke 21 are pole blocks generally designated 30 and 3|, each of which is provided with a square notch 32 adapted to interfit with the squared ends 33 of the yoke 27!. The pole blocks are secured to the yoke by screws and nuts 34 and 35, as best shownin Fi 4=.'

The pole blocks are preferably made of Sveaelectrical iron because of its purity and low reluctance. The blocks have vertically alined apertures 36 which are coaxial with thecore opening 31 of the coil and each block is counterbored from its inner face, as indicated at 38 to receive pole sleeves 39 and 40, respectively, also of high grade electrical iron. The inside diameter of the pole sleeves is the same as the diameter of the apertures 36 so that the mercury switch within the pole sleeves may be vertically adjusted for position without being fouled by the pole pieces.

A. brass sleeve 4! separates the pole sleeves 39 and." and has an inside diameter slightly less than the outside diameter of the switch envelope l3 so that when the switch envelope is in place, the brass sleeve frictionally engages the envelope and holds it in adjusted position.

- The pole blocks 30 and 3i are preferably cold drawn and after they have been machined, they are annealed at 1750" F. for approximately five hours. They are then finished with Udylite.

The pole sleeves 39 and 40 and the component laminations of the yoke 21 are likewise annealed and finished with Udylite.

Both pole blocks are vertically split as indicated at 42 between the vertical apertures 36 and the notches 32. As a result, the portions of the pole blocks which are secured to the yoke 21 act as jaw arms in gripping the yoke. This is quite important as it is necessary to have intimate contact between the yoke and pole blocks if efl'icient operation of the relay is to be obtained.

Ithas heretofore been the practice to have the pole sleeves directly connected to the ends of the yoke, as shown for example in Larson Patent 1,967,951. It is a rule that after any machining on parts of an iron circuit, there must be subsequent annealing, and since each lamination of the yoke must be separately plated after annealing, it is obvious that there is considerable complication in having to mill the ends of the yoke, then anneal, then plate the laminations separately, and finally assemble the laminations in proper order to make up the yoke.

The iron circuit of this invention, however, has the advantage that 'no machining of the yoke is necessary so that the individual laminations may be annealed and plated and then assembled with the rest of the iron circuit.

The relay of this invention also has the distinct advantage that the switch is mounted within the coil where the magnetic flux is strongest, and where minimum power is required for operating the switch. Furthermore, the air gap between the top of the armature sleeve 20 and the lower end of the top pole sleeve 39 is located at the center of the coil where the concentration of flux is at its maximum. By locating the air gap at this point, the top of the switch envelope lies within the top pole block 30 with no portion extending above, thus affording protection against breakage of the glass envelope. The bared end of the electrode I5 is located just below the coil Ill and when the inner ceramic sleeve IQ of the displacer is made of glass, it is desirable to provide a window opening 43 in the bottom pole block and lower pole sleeve so that the operation of the switch parts may be observed.

The pole blocks, being of substantial cross section and extending an appreciable distance beyond the switch envelope, evenly distribute the flux around the switch envelope, thus preventing horizontal components of flux from acting upon the armature sleeve 20 and increasing the friction of the displacer within the switch envelope. The pole blocks 30 and 3| may be rounded at their ends for greater efiiciency if desired.

The vertical splits 42 in the top and bottom pole blocks prevent eddy currents from travelling around the switch envelope when the relay is being operated on alternating current and thus enable the relay to be used efliciently with this type of current.

It is obvious that the inveniion may'be variously modified within the scope of the appended claims.

I claim:-

1. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition oi the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks. of substantial cross section attached to said portions and projecting over the core opening 01 the coil, and pole sleeves in the core opening attached to the pole blocks and separated from each other by an air gap located approximately at the'center oi the coil.

2. In a. mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks of substantial cross section attached to said portions and projecting over the core opening of the coil, and pole sleeves in the core opening attached to the pole blocks and separated from each other by an air gap located approximately at the center of the coil, said pole blocks being recessed to receive the pole sleeves.

3. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks attached to said portions and projecting over the core opening of the coil, and pole sleeves in the core opening attached to the pole blocks and separated from each other by an air gap located approximately at the center of the coil, said pole blocks having alined apertures that are counterbored for receiving the pole sleeves.

4. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks attached to said portions and projecting over the core opening of the coil, and pole sleeves in the core opening attached to the pole blocks and separated from each other by an air gap. located approximately at the center of the coil, said pole blocks having alined apertures that are counterbored for receiving the pole sleeves.

5. In a mercury switch relay, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks attached to said portions and projecting over the core opening of the coil, and pole sleeves in the core opening attached to the pole blocks and separated from each other by an air gap located approximately at the center of the coil,

said pole blocks having alined apertures that are counterbored for receiving the pole sleeves, and a brass sleeve separating the pole sleeves and frictionally engaging the walls of the switch envelope for supporting the latter within the core opening.

6. In a mercury switch relay, a relay coil hm ing a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the. 7

and an opening in the bottom pole block permitting observation of the switch parts.

7. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening andcomprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil; top and bottom pole blocks attached to said portions and projecting over the core opening of the coil, said pole blocks being split horizontally and formed with jaws adapted to engage said prjoecting portions of the iron circuit.

8. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope; a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and belowthe coil, top and bottom pole blocks attached to said portions and projecting over the core opening of the coil, each of said pole blocks having a circular aperture and a vertical split extending from one face of the block to the aperture.

a 9. In a mercury switch relay oi. the class described, a switch element, a relay coil and an iron circuit associated with the element and coil, said iron circuit including a pole block having a square.-

notch in one face, a circular opening through the block,- and a vertical split connecting the open-- ing and the notch.

10. In a mercury switch relay of the class described, a switch element, a relay coil and an iron circuit associated with the element and coil,

.said iron circuit including a pole block having a square notch in one face, a circular opening through the block, and a vertical split connecting the opening and the notch, said opening being counterbored for a portion of its length.

11. In a mercury switch relay, a relay coil having a core opening, a mercury switch mounted within the opening and comprising a switch envelope, a mercury fill, spaced electrodes in the envelope, and a magnetically responsive displacer for shifting the mercury level to change the condition of the electrical circuit through the electrodes, and an iron circuit associated with the coil and the switch having portions extending above and below the coil, top and bottom pole blocks of substantial cross section attached to said portions and projecting over the core opening of .the coil, and pole sleeves in the core open ing associated with the pole blocks for fixing the position of the air gap between the pole blocks, said pole blocks having aligned apertures adapted to'receive' the switch and having sufficient mass encircling the switch so that the tendency of the displacer to move laterally upon energization of the coil is-substantially eliminated.

UNO C. HEDIN. 

